student_scores = {
    "Anna": 90,
    "Tom": 78,
    "Jerry": 85,
    "Lucy": 92
}

print(student_scores.keys())  # 查看所有学生
print(student_scores.values())  # 查看所有成绩

student_scores.setdefault('ZR', 9999)  # 添加新学生
print(student_scores)

student_scores['ZR'] += 1  # 更新学生成绩

student_scores.pop('ZR')  # 事了拂衣去，深藏功与名
print(student_scores)

print(student_scores.get('ZR', '他曾经是个王者'))
print(student_scores['Anna'])
